The invention relates to a method for the continuous production of an endless string of polyurethane reactive plastic material,                a) at which at first the reactive components polyol and isocyanate are conveyed to a mixer in a metered manner,        b) at which then the reactive components are mixed in the mixer to a reactive mixture,        c) which subsequently the reactive mixture is discharged into the environmental atmosphere and        d) at which a first sheet section made from a plane, flexible material, especially a paper, foil or textile sheet, which is conveyed continuously into a transporting direction is coated with the reactive mixture.        
A method according to the generic kind is disclosed in DE 2006 051 311 A1. This method can be used for different applications, for example for the production of flexible soft bloc foam, of closed-cellular hard block foam, of isolation panels and of half-finished products made from thermoplastic polyurethane. This method can be carried out with a plurality of facilities with different facility concepts. Continuously working bloc foam facilities for flexible foam systems as well as for hard foam systems are examples of such facilities.
Furthermore, the present invention relates also to facilities for the continuous production of sandwich panels or isolation panels on so-called double panel belt systems.
An object which recurs always again at those facilities respectively at the corresponding methods is the optimized application of the reactive mixture onto the substrate which protects the components of the device from pollution with reactive mixture. With respect to the application technique different aspects have to be considered hereby:
At first no air bubbles should be brought into the reactive mixture.
Furthermore, the application technique must ensure a distribution of the reactive mixture along the whole production width (width of the substrate).
Hereby, also an age distribution of the reactive mixture which is as homogeneous as possible along the production width should be ensured.
After the reactive mixture is discharged into the environment atmosphere possibly no stationary device components should be bathed with reactive mixture due to the fact that the reactive mixture is normally a material with good adhesive properties to so ensure a long and reliable production of the device.